The present invention pertains to compositions and methods for using such compositions in the removal of contaminants from substrates and equipment, particularly in the semiconductor fabrication industry. More particularly, the present invention is directed to the use of xcex2-diketonate-containing compounds in processing (e.g., planarizing, polishing, cleaning) compositions and methods.
A large fraction of yield losses in wafer fabrication or processing of semiconductor devices is attributed to contamination. Contaminants can be organic or inorganic particles, films or molecular compounds, ionic materials, or atomic species. Particularly problematic, however, is contamination from abrasive particles used during processing, such as planarization. For example, during chemical mechanical planarization or polishing (CMP), a rotating substrate of semiconductor material is held against a wetted planarization or polishing surface using a liquid slurry under controlled pressure and temperature conditions. The liquid typically consists of an abrasive component, such as alumina, silica, or similar particulates, although, alternatively, a pad could include the abrasive component. Once the planarization or polishing is complete, abrasive particles typically remain on the surface of the substrate.
Thus, the primary contaminants that need to be removed from the substrate surface during/after processing, such as planarization or polishing, and prior to subsequent processing steps are alumina, silica, and oxides. Other contaminants that can also be problematic include ionic, atomic, or molecular species containing sodium, potassium, lithium, calcium, boron, manganese, sodium, titanium, zirconium, magnesium, iron, copper, nickel, gold, silicon, and aluminum. Such contaminants may diffuse into the surface of the substrate and down fracture paths.
Also, the presence of contaminants during substrate processing has become particularly problematic in high density, large scale integration (LSI) technology. For example, contaminants can cause a device to fail by improperly defining features within the integrated circuit, creating unpredictable surface topography, inducing leakage currents through insulating layers, or accelerating device wearout.
SC-1 wet cleaning solutions (mixtures of NH4OH, H2O2, and H2O in a volume ratio of 1:1:5 typically) used in an xe2x80x9cRCA cleanxe2x80x9d are commonly used to clean wafer surfaces during processing. xe2x80x9cRCA cleanxe2x80x9d has been the primary cleaning process for the semiconductor industry for nearly 30 years. RCA cleans reportedly remove particles and organic contaminants on semiconductor surfaces without significantly attacking the semiconductor surface. RCA cleans commonly include a series of two baths (with a third optional bath) for immersion of the wafers. The first bath typically contains the basic SC-1 wet cleaning solution. The second bath is optional and typically contains hydrofluoric acid (HF) or buffered HF for removal of oxides formed from the H2O2 in the SC-1 wet cleaning solution. Finally, the third bath is called an SC-2 wet cleaning solution, typically containing an acidic halogen solution (e.g., HCl along with H2O2 and H2O in a volume ratio of 1:1:6 typically) for removing heavy alkali ions and cations from the wafer surface. After immersion in each bath, the wafer surfaces are commonly rinsed in deionized water and optionally dried.
One problem associated with using such wet cleaning solution baths is that the chemicals need to be replenished frequently due to their reaction with particulates on the wafer surfaces and evaporation into the atmosphere. This is both costly and time-consuming. Recently, tetramethylammonium hydroxide (TMAH) as been utilized in wet cleaning solutions. TMAH has been shown to reduce chemical consumption, and, thus, lengthen the bath life. TMAH is reported to lengthen the bath life because it is not as readily evaporated from a standard wet cleaning solution as is ammonia in an SC-1 wet cleaning solution.
It has also been reported that phosphonic acid chelating agents added to an SC-1 wet cleaning solution reduce certain metallic contamination deposition on a silicon substrate. This conclusion was reached in the article entitled xe2x80x9cThin-Oxide Dielectric Strength Improvement by Adding a Phosphonic Acid Chelating Agent into NH4OHxe2x80x94H2O2 Solutionxe2x80x9d by Akiya et al., J.Electrochem. Soc., Vol. 141, No. 10, October 1994.
Also, it has been demonstrated that water soluble multidentate chelating agents, particularly water soluble bidentate ionic chelating agents, such as 1,2-ethylenediphosphonic acid (EDP), can be used during planarization processing to remove metal ion contaminants, as disclosed in U.S. patent application Ser. No. 08/682,308, filed on Jul. 17, 1996, entitled xe2x80x9cA Planarization Fluid Composition Including Chelating Agents and Planarization Method Using Same.xe2x80x9d
The JTB-100 wet cleaning solution in a xe2x80x9cBaker Cleanxe2x80x9d has also been used as a replacement for the RCA clean, as described by Cady et al. in xe2x80x9cRCA Clean Replacement,xe2x80x9d J. Electrochem. Soc., Vol. 143, No. 6 (June 1996). In this wet cleaning solution, TMAH-based alkaline material has been used in conjunction with a carboxylate buffer to remove particulate contaminants from wafer surfaces. This cleaning solution was sprayed on wafer surfaces, followed by a rinse in deionized water. The JTB-100 wet cleaning solution replaced the SC-1 and SC-2 wet cleaning solution baths in a conventional RCA clean. An optional bath containing a solution of H2SO4/H2O2/H2O in a volumetric ratio of 4:0.2:0.8 and an optional bath containing HF or buffered HF were used prior to the JTB-100 wet cleaning solution.
Another problem that has not been adequately addressed is the leaning of the planarization or polishing surface both during and after processing. When planarization or polishing surfaces are used with abrasive slurries, it is important to prevent the buildup of abrasive particulates and other contaminants on such polishing surfaces. When abrasive pads are used, it is important to prevent the buildup of metal and metalloid ions and oxides, for example, on such abrasive pads. Such contaminants shorten the effective lifetime of processing equipment and should be removed to ensure precise processing of substrates during planarization or polishing without excessive contamination of the substrates.
Thus, compositions and methods are still needed to reduce, for example, the amount of metal and metalloid ion and abrasive particulate contamination of, for example, the substrate being processed and the processing equipment used. The present invention as described below provides such compositions and methods.
The present invention provides compositions and methods for processing substrate surfaces and equipment during planarizing, polishing, or cleaning processes, for example. The substrate surface can be a semiconductor-based substrate surface, among many other possibilities. Thus, the compositions of the present invention can be used at various places in processing a semiconductor-based substrate, for example, such as before, during, or after, planarization. The compositions include one or more xcex2-diketonate-containing compounds of the following formula (Formula I): 
wherein each R1, R2, R3, and R4 is independently H or an organic group. Preferably, each R1, R2, R3, and R4 is independently H, or a hydrocarbyl group, optionally containing one or more heteroatoms (e.g., oxygen or nitrogen), fluorine atoms, or functional groups (e.g., a carbonyl group, a hydroxycarbyl group, or an aminocarbyl group).
The present invention also provides a method of processing a substrate surface. This method includes processing the substrate surface with a processing composition comprising a xcex2-diketonate containing compound of Formula I. When processing a substrate surface using planarization or polishing, the processing composition can also include an abrasive component, such as silica or alumina, or an abrasive planarization or polishing surface can be used instead of, or in combination with, an abrasive processing composition.
As used herein, the term xe2x80x9cprocessingxe2x80x9d also includes cleaning. Thus, a preferred method of processing a substrate surface involves cleaning the substrate surface. In one embodiment of the present invention, a method of processing a semiconductor-based substrate surface is provided which includes the steps of planarizing the substrate surface, and cleaning the planarized substrate surface with a composition comprising a compound of the Formula I.
The present invention also provides a method of cleaning processing equipment, such as planarization processing equipment. The method comprises cleaning the processing equipment with a composition comprising a compound of Formula I. In one embodiment, the method includes providing a planarization surface, such as an abrasive pad or a polishing pad, and, cleaning the planarization surface with a composition comprising a compound of Formula I. This cleaning process can be done during or after planarizing a substrate surface with an abrasive component.
Also provided is a processing composition for use in fabricating semiconductor-based structures, the processing composition comprising a liquid carrier and a compound of Formula I. It will be understood by one of skill in the art that the processing compositions of the present invention can include one or more compounds of Formula I.